Patrick Stewart as Vladimir, Simon Callow as Pozzo and Ian McKellen as Estragon in Waiting for Godot. Photograph: Tristram Kenton

West End theatres are packing in more people than at any time since records began 25 years ago – and it is not just thanks to musicals, figures released today show.

The Society of London Theatre (SOLT), which compiles the figures for all 52 major theatres in central London, said that in the first six months of 2009 – up until 18 July – there were 7,627,426 visits. That is 2.5% up on 2008 which was itself a record year. Box office receipts are also 3.5% up.

While musicals still dominate the West End, accounting for 61% of the figure, play attendances, at 1,886,586, represented a quarter of all visits. And that was up by 19% on last year.

The society attributes the healthy figures to the strength of what's on, as well as the fact that more people are staying in the UK this year. The figures also give succour to those who argue that in times of economic uncertainty people want to be entertained, though not necessarily in a "make me cheerful" way.

SOLT's president, the West End producer Nica Burns, was "completely surprised" at the figures. "I said in our annual report that if we happened to be 10% down on last year than I would be happy. So to be up on last year, I'm obviously ecstatic."

The quality of plays had been a contributing factor to the boom and serious drama has been doing well across London from Phedre at the National, to Waiting for Godot at the Haymarket, to the Bridge Project plays at the Old Vic, to Arcadia at the Duke of York's. "Plays in London are going through a special period of excellence and the audiences are flocking," said Burns. "And there is breadth to what is on. If you were coming to London for a week you would have a hard time fitting in everything you wanted to see."

Some critics have complained that West End producers have, more recently, not been willing to take enough risks and widen what's on offer. But Burns said that was unfair. "We do try and give audiences variety but this is not like manufacturing Tetrapak. If you could guarantee something was going to be successful you would have a lot of very rich producers."

The slow rise of Sunday performances – notably at the National Theatre and for West End plays such as Waiting for Godot and Hamlet – has also contributed to the healthy figures.

SOLT's chief executive Richard Pulford called the figures "a real cause for celebration". He added: "At a time of economic uncertainty, it's marvellous that people aren't retreating into their shells. Instead they're choosing to come together in our theatres to be entertained, challenged and uplifted."

West End plays also gained Tony awards success on Broadway with awards for Billy Elliot, Mary Stuart and The Norman Conquests. And there also further West End theatre to look forward to: Anna Friel in Breakfast at Tiffany's for example and Richard Briers in Samuel Beckett's existential classic Endgame.